1. Field of the Invention
This invention relates to a stapler, in which the stapling operation can be performed by driving a staple through sheets of paper, etc., with a comparatively small force.
2. Related Art
Staplers are known without the need of listing a specific example. A typical stapler includes three members, i.e., an operation frame, a staple magazine and a base frame which are all pivotally attached together at their rear ends. In operation, the staples stored in the staple magazine are pressed against a staple receiving board, which is disposed at the front end of the base frame and driven, one by one, into sheets of paper by means of a staple pressure lower piece, which is disposed at the front end of the operation frame. In order to facilitate this stapling operation in a stapler of the known construction through the operation frame, a handle frame is disposed at the outer side of the operation frame. This handle frame is provided at an intermediate part of its rear end in the back and forth direction of the handle frame with a pin. This pin is brought into engagement with a slot which is formed in an intermediate part of the operation frame so that the handle frame is linked to the operation frame. At the time of stapling operation achieved by pressing the front end of the handle frame, the control frame is pivotally rotated under the effect of lever action serving the pin part as a point of action. Owing to this construction, the pressing force to the front end side of the handle frame is exhibited greatly on the operation frame side and therefore, the driving operation (stapling operation) of the staple can be performed with a comparatively small force (for example, see Japanese Patent Application Laid-Open No. 2002-28877).
However, the above-mentioned conventional techniques have the following problems. Since the operation frame is pivotally rotated by moving the pin, which is disposed at the handle frame side, through the slot, which is formed at the operation frame side, the pin and the edge part of the slot are mutually pressed against each other and deformed. This deformation causes the pressing force applied to the staple to be reduced, thus resulting in deterioration of the original function which the stapler inherently has.
The present invention has been accomplished in view of the above problems.